Plastic plug with overcap



FIG. 1 is a perspective view of a plastic plug with overcap, showing my new design;

FIG. 2 is a front elevational view thereof; the rear elevational view and the left and right side elevational views being the same;

FIG. 3 is a top plan view thereof; and,

FIG. 4 is a bottom plan view thereof. 

The ornamental design for a plastic plug with overcap, as shown and described. 